The following patent documents were identified through a research on the prior art in the field of the invention:
(D1) The CN 1800540 A—D1 describes a hollow reinforced concrete slab comprising hollow elements of reinforced concrete. The elements are concreted “in situ” and reinforced with a concrete rib. The hollow elements comprise a formwork cavity. The invention can be applied to various solutions of molded and reinforced concrete, such as roofs of buildings, foundation slabs, walls and bridges;
(D2) CN 203401620 U—D2 is a utility model which discloses a connector for steel bars and is designed with the objective of solving the problems associated with the reinforcing steel bars, which may include the use of electrical and mechanical equipment, before or during the construction, to connect the reinforcing threaded steel construction, to connect the reinforcing threaded steel bars used in construction. The invention comprises a casing tube, internal screw threads, and fixing screws and is characterized in that the internal threads are embedded in the inner wall of the casing tube; and in that it includes a plurality of fixing screws arranged in the location corresponding to the internal screw threads;
(D3) CN 203008388 U—D3 discloses a steel support bar fixed in a reinforced concrete slab casted “in situ”. It comprises a sleeve tube, an end cap, a support rod, a block, a locking bar, a nut and a locking latch, in which the lower part of the sleeve tube is toothed while the lower middle part of the sleeve tube is closed.
The present invention relates to telescopic bars for load transmission anchored and cast in cement concrete slabs, which allow the transmission of loads from a slab to the adjacent slabs, and not only ensure the transmission of said loads but, simultaneously, also prevent the differential settlement of those slabs.
The telescopic function of the bar which allows its support between slabs created a new possibility of obtaining prefabricated floorings easy to manufacture and assemble in situ, creating a new concept in the construction of roads, ports, airports, railways, industrial areas, etc., which distinguishes the present invention from the closest state of the art.
Additionally, the possibility of obtaining concrete roads with these telescopic bars, and the fact that the constituent slabs can be prefabricated, remarkably reduces the environmental impact since the constituent elements do not release pollutants, neither in the manufacture nor in the application and use.
Once the telescopic bars for load transmission are alternately arranged and anchored in the base of the slabs along the backrest joints, the bending stresses in the upper edge of said slabs decrease and a rotation about its axis in the vertical direction of said joints is allowed.
Thus, any unevenness in the upper joint edge formed by the separation of the slabs can be eliminable, whether these slabs are pre-molded or not.
Additionally to the above, it should be noted that if the foundations suffer differential settlements due to its elastic function or by erosion of the same, these concrete slabs will be able to follow these movements, ensuring the leveling in the axis of the backrest joints, and allowing the slabs to rest entirety on the foundation, thus being subjected to compressive stresses and reducing the stresses generated by the flexion/traction forces caused by the transmission of the loads.
As can be seen, these bars which allow prefabrication of concrete slabs for ground floors over elastic foundations also allow a further possibility consisting in obtaining over-elevations at the outer radius of curves, which are so far impossible by techniques of in situ concreting due to the sag of the concrete thus creating shrinkage cracks and putting slabs out of use.
This possibility results from the manufacture of slabs in molds with predefined curvature, thus maintaining a perfect planimetry even when the over-elevation bend of the curves is marked.
The use of telescopic bars, since they allow prefabrication of concrete slabs, also allow obtaining curves with constant radius after topographical information, increasing the safety and convenience of road traffic.
Thus, we can conclude that these two advantages of over-elevations of the outer radius of the curve and constant radius will save countless lives in the future and increase the driving speed—thus increasing savings in the transport of commodities, people and goods and increasing savings in the fuel consumption.
The innovation of the invention consists in the ability of creating a flexible load transmission support, after the execution or placement of prefabricated slabs of cement concrete, for building ground floors in highways, roads, airports, ports and industrial areas.
This possibility of having telescopic bars which extend or are retracted underneath contiguous slabs, not only allows to place the slabs as well as to remove them whenever necessary (repair the foundations or placing tubes for underpasses, etc.), thus allowing obtaining removable slabs.
These removable slabs allow placement (mounting) through the use of cranes over any land or deformable material (EPS type, etc,) in any kind of weather conditions (freezing, rain, sun, wind, day, night, etc.).
In summary, the telescopic bars object of the present invention allow the pre molding of slabs with numerous technical and economic advantages compared to the prior art, such as:                a) Speed of construction:                    i. Placement of the pre molded slabs using a crane. Manpower of this operation=3 men;            ii. Placing in work shifts, since the slabs are already prefabricated, allowing a continuous placing without interruption;            iii. Placing with any atmospheric weather (rain, freezing and defrosting, positive and negative temperatures, sun, fog, etc.);            iv. Immediate use;            v. Eliminating manpower and heavy equipment for in situ construction;                        b) Economy                    i. Absence of manpower to build in situ;            ii. No heavy equipment;            iii. Immediate use;            iv. Useful life span exceeding 50 years;                        c) Foundations                    i. Soil with low support, less than one kilogram/cm3             ii. Expansive soils            iii. Artificial soils EPS, stabilized soils (cement, lime, etc.)                        d) Quality of the concrete                    i. Concrete of high resistance and easy control in manufacturing;            ii. Concrete of high mechanical wear strength with optimized prefabricated ribbing;            iii. Concrete manufactured and molded under optimum conditions of temperature and humidity;                        e) Levelling of slabs and planimetry: optimized to 0 mm;        f) Applications:                    i. Curves with high over-elevations with the required angle;            ii. Curves with constant radius;            iii. Large tilt angles (up and down);            iv. Coverage of embankments;            v. Ideal for construction of railways, roads and highways, either in urban or open fields, ports and airports and industrial areas, etc.;                        g) Adherence and security controlled in project and in factory: ribbing with optimized prefabrication;        h) Environmental impact: The possibility of obtaining concrete roads with these telescopic bars, and the fact that the constituents can be prefabricated slabs, remarkably reduces the environmental impact since the constituent elements do not release pollutants neither in the manufacture, nor in the placement and use.        